Outboard propelling system comprising an adjustable propeller



United States Patent [72] Inventor 3,273,656 9/1066 Bird l70/l60.32Stockholm, Sweden 3,368,517 2/1968 Macdonald et a1. A. 1 15/41 [2]]Appl. No. 849,547 3,376,842 4/1968 Wynne 115/41X [22] PrimaryExaminerTrygve M. Blix commuauon of Altorney-Pierce Schaffler & ParkerJan. 1,1961 abandoned. v W

[45] Patented Oct. 20, 1970 [73] 1 Asslgnee i scama'vabs ABSTRACT: Adrive assembly for high speed boats of rela- Sodertahe, Sweden, l 1 h, bd d acorporafion fsweden ive y great size dVll'lg an engine mountc inoar s an an outboard propelling system. The steering of the boat 15 ef-[32] Priority Jan. 9, 1967 fected by turning the outboard system about asubstantially [33] Sweden [31 270/67 vertical pivot located outside thestern board of the boat. The

outboard ro ellin s stem is furthermore ada ted to be P P g y P pivotedbackwards relative to the course of the boat about one 5 OUTBOARDPROPELLING S S COMPRISING or more horizontal pivots. The outboardpropelling system is AN ADJUSTABLE PROPELLER secured to the inboardengine which has its shaft coaxial with 1 Claim, 6 Drawing Figs. theinput drive shaft of the outboard propelling system. This input shaftextends through a hole in the stern board of the [52] U.S.Cl 115/35 boatand is driven synchronously with the engine Speed by lnt. means of anengageable and disengageable clutch p d 86% 5/06 between said shafts.The inboard drive shaft transmits torque ofSearch l means of amechanical transmission to a horizontal 41 propeller unit rotatablymounted in the lower portion of the outboard propelling system. Thepropeller has a plurality of [56] References C'ted blades adapted to beturned between two end positions for al- UNITED STATES PATENTS ternativeahead and astern propulsion of the boat, the blades 2,809,605 10/1957.Russell ll5/34X being hydraulically operable by a piston roddisplaceably 3,148,735 9/1964 Miller et a1. l70/l60.32 mounted in aportion of a propeller shaft, said portion of the eman ro e ers at emint e ormo a rau ICC in er. 3253 659 5/1966 S 170/16032 p p 11 h f b g hf f hyd 1' yl' d F 9 w Ce 1 l 2 15 31 if 2] I 37 22 l r 13 182519 L g I40 1 i t 2D 17 I n i! 1! L3 i) O I lKDII I M 9 s4 3 in 55 7 i 5) 25c 12C 30 29 .Jze oillllllllp 25 I l l I n lillllll i l: I 1 1 l l L o l \I Ia. 7

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Sheet 3 015 INVENTOR. NIL: Fer E/(man mfimkk mow OUTBOARD PROPELLINGSYSTEM COMPRISING AN ADJUSTABLE PROPELLER The present application is acontinuation of application Ser. No. 696,400 filed Jan. 8, I968 and nowabandoned.

This invention relates to a driving mechanism for high speed,comparatively large boats having an inboard suspended engine and anoutboard propelling system. In particular the invention relates to suchdriving mechanisms in which steering of the boat is effected by turningthe outboard propelling system about a substantially vertical pivotlocated outside the stern board of the boat and wherein the outboardpropelling system is also adapted to be turned backwards in thedirection of the course of the boat about one or more horizontal pivots.

Outboard propelling systems of this kind have previously beenconstructed for comparatively small boats having an engine power ofbetween 50 and 150 HP. However, development has tended toward everincreasing sizes of boats, and the demand for outboard propellingsystems for comparatively large pleasure boats, taxi boats and similartransport boats and landing boats for naval purposes has increasedenormously during the last decade.

The reason therefore is believed to be due to the fact that an outboardpropelling system considerably reduces the initial costs as comparedwith a conventional inboard installation in which a propeller shaftbelow the boat is connected to the engine via a bevel gearing or thelike. Further, an outboard propelling system has considerable advantagesfrom the point of view ofhandling and maneuvering and thenavigability ofan outboard propelling system-equipped boat in shallow water is superiorto a boat having firmly attached drive members. Since the outboardpropelling system usually is adapted to be turned backwards in thedirection of course of the boat. damages to this system in case ofgrounding are eliminated or mitigated. If, nevertheless, the propellercasing or part thereof should be damaged the propeller assembly of mostof the prior art outboard propelling systems can easily be turnedupwards above the water line and exchanged or repaired.

Conventional outboard propelling systems coupled to inboard engines areconstructed to be secured to the stern board of the boat. Consequently,all stresses caused by the propelling system are transmitted to thestern board which has to be provided with strong reinforcements.

Further, such propelling systems usually include some sort of areduction gear which via a vertical drive shaft transmits the enginepower to a propeller shaft which indirectly carries a propeller with aplurality of fixed blades. The direction of rotation of such a propellermust be reversible for alternative ahead and astern propulsion of theboat. For this reason prior art propelling systems are equipped with areversing gear and a friction clutch or the like between the engine andthe propelling system.

In small boats having a power requirement below 150 HP the inconvenienceof the reversing gear is not as manifest as in larger boats. In largerboats having a power requirement above 200 HP it has hitherto beennecessary in each individual case to instal at least two separatecarburetor engines side by side with each engine driving its ownpropelling system. Such a parallel drive has certain advantages from thepoint of view of maneuverability. but its inconveniences are above alltoo high initial costs and the difficulty of obtaining a satisfactoryparallel drive. In addition, the parallel drive results in aconsiderable increase of weight, and the available space in the sternpart of the boat is too much reduced and renders maintenance work on thedriving engines more difficult.

It would of course be possible to replace the cooperating ens.by s sslss1s n t nks .ztnsqu abi y s th boat having a propeller with fixed bladeswould be difficult and besides, the reversing gear with the connected orbuilt-in friction clutch would be too expensive to produce.

The object of this inventjonjs to provide easy maneuverability ofrelatively large high-speed boats having a power requirement between 100and 300 HP with the use of a single driving mechanism comprising aninboard motor and an outboard propelling system. In its broadest aspectthe invention is characterized by the combination of the followingfeatures:

the outboard propelling system is firmly attached to the inboardsuspended engine the shaft of which is coaxial with an input drive shaftof the propelling system, which input shaft extends through a hole inthe stern board ofthe boat and via an engageable and disengageableclutch disposed between said shafts can be specded synchronously withthe engine speed; the inboard drive shaft transmits torque via amechanical transmission to a horizontal propeller unit rotatably mountedin the lower part of the propelling system; and

the propeller has a plurality of blades adapted to be turned between twoend positions for alternative ahead and astern propulsion of the boat,said blades being hydraulically operable by a piston rod displace-ablymounted in a portion of a propeller shaft which portion is in the formof a hydraulic cylinder.

The combination according to the invention which advantageously can beapplied to pusher propellers as well as tractor propellers offersconsiderable advantages due to the fact that its components andfunctions are considerably simplified as compared with previously knowncombination inboard engincs outboard propelling systems. Neither an expensive reversing gear nor other gearings are required, and a frictionclutch provided between the engine and the propelling system is muchless complicated than the conventional disc clutch in propelling systemshaving a propeller with fixed blades.

With the propelling system firmly attached to the engine theinstallation in the boat is facilitated. Due to the elimination of thenecessity of aligning the engine and the propelling system and ofotherwise required readjusting of said parts the invention results inthe advantage that the engine can be elastically suspended in the enginebed resulting in a more silent and smooth operation of the engine. Inaddition, the stern board is relieved and the reaction pressure of thepropeller is taken in the engine bed in a combination according to theinvention.

An additional advantage is due to the fact that the manual control ofthe end positions of the propeller blades for obtaining a favourablepropeller performance in boats of different sizes and loads also resultsin a better fuel economy of the engine. In the combination according tothe invention the engine is preferably a diesel engine which reduces thedanger of tire onboard the boat and results in lower operating costs andhigher reliability in operation as compared with a petrol engine.

Within the scope of the annexed claims the invention can be embodied inmany different ways, and due to the great flexibility of the embodimentillustrated in the annexed drawings and described hereinbelow thisembodiment is only an example of carrying the invention into effect.

In the annexed drawings, FIG. 1A is a longitudinal sectional view of thepropelling system according to the invention attached to an inboarddiesel engine, FIG. 1B shows a detail of FIG. llA on an enlarged scale,FIG. 2 is a cross-sectional view taken along the line A-A in FIG. IA andillustrates the members by means of which the outboard section of thepropelling system can be turned laterally upwards into a position abovethe water line, FIG. 3 is a sectional view taken along the line B-B inFIG. 1B and illustrates the mechanical shifting mechanism for thepropeller blades, FIG. 4 is a cross-sectional view along the line C-C inFIG. IA and illustrates the mem bers comprised in the steering mechanismof the propelling system, and FIG. 5 is a sectional view taken along theline D-D in FIG. 1A and shows how the steering operation isservo-controlled.

With respect to its characteristic function the propelling systemaccording to the invention comprises an inboard section and an outboardsection. By means of flanges and screws the inboard section is firmlyattached to the flywheel housing of the engine I. By means of afrontbearing, not shown, and a rear attachment 3 the engine 1 is in aconventional manner elastically suspended in an engine bed in the sternpart of a boat 4.

Provided between the output shaft, not shown, of the engine 1 and aninput shaft 6 of the propelling system is a friction clutch 5 by meansofwhich the input shaft 6 can be connected to and disconnected from theengine 1. The friction clutch is of any suitable conventional type andneed not be described in detail.

The clutch 5 is enclosed in a case 7 which is the external cap of theinboard section of the propelling system. By means of the above namedflanges and screws, not shown, the clutch case 7 is firmly attached tothe flywheel housing 2 of the engine. Consequently, the flywheel housingsupports the whole of the propelling system. Beginning from the flangedconnection with the flywheel housing 2 the clutch case is first conicaland then merges into a sleeve-shaped portion 7a which extends through anupper hole in the stern board 8 of the boat.

in order to render possible inspection of the clutch 5, the upperportion of the wall of the clutch case 7 has an opening which in normaloperation is closed by a protective cover 9.

At the outer end of the conical portion of the clutch case 7 there isprovided an integral downwardly extending shield 71) secured to twobrackets 10 each of which has mounted thereon a supporting rod 10a.These supporting rods extend through lower holes in the stern board 8 ofthe boat and their outer ends bear on the outboard section of thepropelling system.

The three holes in the stern board 8 are sealed by elastic sealing rings11 and 12 which are secured to the stern board and surround the sleeve7a and the rods 10a, respectively.

Rotatably mounted in the sleeve 7a of the clutch case is a unit heldtogether by axial screws, not shown, and consisting of two hubs l3 and14 extending from different sides of the sleeve 7a and located onewithin the other. Each hub is connected to a ball bearing 15 and 16,respectively, by means of which the input shaft 6 is mounted in thepropelling system.

By means of splines a shaft 17 is displaceably mounted in the outer endof the shaft 6. By means of a double universal joint 18 and flangedscrew joint 19 the shaft 17 is relatively nonrotatably'connected to arotatably mounted external drive shaft 20 which is aligned with theshafts 6 and 17 and the mounting of which will be described hereinbelow.

The hub 14 has an external flange 14a which by means of a flange andscrews, not shown, is connected to a front casing 21 of the outboardsection of the propelling system. The outboard section is rotatablymounted as a unit relative to the inboard clutch case 7 secured to theengine 1. To this end the sleeve 7a of the clutch case is provided witha vertical screw 31 which along a secant extends through the wall of thesleeve 70 and is in mesh with a peripheral thread on the hub 13. If thescrew 31 is turned by a crank, not shown, the composed bearing unit 13,14 in the sleeve 7a will be turned together with the outboard section ofthe propelling system.

The front casing 21 carries the control means of the outboard sectionwhich means are in the form of a unit composed of a plurality ofindividual parts which substantially comprise a steering mechanism 28, arear casing 26 including power transmission means, and a propellerassembly 24. For the sake of convenience this unit will be termedhereinbelow control casing 22.

The control casing 22 can carry out two different kinds of turningmovement relative to the front casing 2], namely for performing thesteering action and, for the sake of safety, for preventing too greatdamages to the propeller assembly in case of grounding. in both cases aV-shaped steering fork 27 comprised in the steering mechanism 28 is theconnecting member between the two casings 21 and 22.

As will be seen from FIG. 4, the steering fork 27 is movably mounted ontwo pivots each of which extends through a bearing member 21a at therespective vertical wall of the front casing 21 and is received in athrough hole in the respective end of the limb of the V-shaped steeringfork inside the front casing 21.

The steering fork 27 carries the other members of the steering mechanism28. A Ushaped reinforced bearing bracket 32 is mounted for turningmovement on a vertical pivot 23 which is axially nondisplaceably mountedfor turning movement in a through hole coinciding with the vertical axisof symmetry of the V-shaped steering fork 27. The bearing assemblycomprises ball bearings 33 secured to the ends of the respective forklimbs. The upper limb 32a of the bearing bracket 32 is mounted above thebifurcation of the steering fork 27 and the lower limb 32b is fittedinto a horizontal recess in the steering fork 27.

The bearing bracket 32 has two double attachments 32c which extend fromthe web of the bracket and by means of two pins 35 or the like areconnected to two hydraulic cylinders 35 adapted to be turned about thepins 35. The piston rods 34a of the hydraulic cylinders are received inexternal recesses in the lower sides of the steering fork 27 and areheld therein by through pins 36 which by means oflocking pins aresecured in the steering fork 27. Under the action of the hydrauliccylinders 34 the bearing bracket 32 is turned about the vertical pivot23, and a unit secured by means of screws, not shown, to the bearingbracket 32 and consisting of the rear casing 26 and the propellerassembly 24 takes part in this turning movement.

The mode of operation of the hydraulic cylinders 34 is known in the art,and the special embodiment of the members comprised in the propellingsystem will be explained in connection with the following description ofthe supply of servooperating hydraulic fluid to the means for effectingahead and astern propulsion of the boat 4.

There are required four oil outlet conduits, not shown, from the controlmembers of the boat. These conduits communicate in a conventional mannerwith a corresponding number of inlet openings l-lV in the wall of theinboard part of the sleeve 7a of the clutch case. These inlet openingscommunicate with internal ducts in the hub 14. The ducts open at theflange 14a and extend into closed ducts, not shown, in the wall of thefront casing 21. From FIG. 4 it will be seen that two pairs of ducts atthe flange 14a are located on either side of a line of symmetry. Theducts are separated from each other and provide a pair of inlet and apair of outlet passages of opposite functions, in the following, onlyone duct of each kind will be described.

The ducts l and Ill enclosed in the front casing 21 communicate withradial inlets to eccentrically disposed axial ducts in the pivot 24. Thelast named ducts are closed at their respective ends but communicate viaradial outlet openings with ducts in the steering fork 27. The duct 1opens into a dead end hole in the pin 36. This dead end holecommunicates radially with a through hole in the piston rod 340 mountedon the pin 36 and opens into the high pressure chamber of the hydrauliccylinder 34, which high pressure chamber is defined between the piston34b and the rear end wall 340 of the cylinder.

Upon supply of pressure fluid through the conduit i into the highpressure chamber the hydraulic cylinder 34 will be displaced to theright as viewed in H0. 5 and turn the bearing bracket 32 and the entirecontrol casing 22 about the pivot 23. Since both hydraulic cylinders arecooperating with each other, the movement of the other hydrauliccylinder 34 will be in the opposite direction. The low pressure chambersof the hydraulic cylinders, Le. the chambers between the pistons and thefront end walls through which the pistons are displaceable, communicatewith each other through a conduit 344' which permits free flow of airenclosed in the respective low pressure chamber and prevents counterpressures from acting during the relative displacements of the pistons.

The duct ill in the pivot 25 and steering fork 27 communicates radiallywith one of two eccentrically located axial ducts in the central pivot23 of the steering fork. These axial ducts are closed at one end andcommunicate via radial outlet openings with two fluid conduits S4, 55.These conduits are connected to the upper limb 32a of the bearingbracket and to the rear casing 26 and secured to two ducts in thepropeller assembly 24. Through these ducts ill and IV the pressure ofthe hydraulic fluid in the propeller assembly 24 is controlled so thatshifting of the propeller blades 51 for ahead and astern propulsion isentirely servo-controlled. This control will be described hereinbelowwith reference to the propeller assembly 24.

Referring to the description of the relative turning movement of thesteering mechanism 28 and the control casing 22 with respect to thefront casing 21, the previously named relative turning movement whichoccurs if the propeller assembly 24 strikes a ground will now also bedescribed in detail.

The control casing 22 which is movably mounted on the two transversehorizontal pivots 25 is normally fixed in operative position relative tothe front casing 21 by means of a safety cotter 29. The safety cotterconnects two lugs on the steering fork 27 with a lower flange 21b of thefront casing. The safety cotter 29 is dimensioned such that it will beshorn off if the propeller assembly 24 strikes a ground, the resultbeing that the entire control casing 22 will be turned backwards aboutthe pivots 25.

To enable this relative turning movement the boundary lines and surfacesof the front casing 21 and control casing 22 must be curved with thecentre of curvature coinciding with the axis of movement. In FlG. 1Athis is represented for horizontal turning movements by the circulararcs for the respective casings 2ll and 22, the common centre of saidarcs lying on the common axis of the pivots 25.

The central member in the control casing 22 is the rear casing 26 whichcomprises a front end wall 27a and a rear end wall 26b in which theouter drive shaft 20 of the propelling system is mounted in ballbearings 37 and 38, respectively. The ball bearing 37 is mounted in ahub 39, and the ball bearing 38 is mounted in a hub 40. Both hubs haveeccentric bearing holes and their flanges are by means of screws, notshown, secured to the respective end walls 26a and 26b.

A contact surface on the outside of the inner end wall 26a and locatedbelow the bearings 37, 39 holds the rear casing 26 in contact with thebearing bracket 32 by means of screws, not shown. Due to the fact thatthe rear casing 26 in a manner not specifically described carries theexternal caps 46, 47 of the control casing 22.and via a base 26c whichinterconnects the lower ends of the end walls and by means of screws,not shown, is rigidly secured to the propeller assembly 24, the entirerear part of the control casing 22 is attached to the bearing bracket32.

Located between the end walls 26a and 26b and axially held in positionby two spacer sleeves and 42 abutting against the ball bearings 37 and38, respectively, is a sprocket 43 secured by splines to the outer driveshaft 20. An endless chain 44 transmits the input torque of thepropelling system from the sprocket 43 to a sprocket 45 mounted in thepropeller assembly 24. The chain can be stretched by turning the hubs39, 40 in the end walls 26a and 26b, respectively.

The propeller assembly 24 comprises a casing 52 the upper part of whichis secured to an intermediate part 30 and the lower part of which issecured to a fin 53. By means of screws, not shown, extending throughthe base 260 the top end of the intermediate part 30 is attached to theunderside of the rear casing 26 so that the propeller assembly 24 as awhole is rigidly connected to the steering mechanism 28 of thepropelling system.

The rotary members of the propeller assembly 24 are movably mounted inthe casing 52 and rotated by the chain Ml which engages the sprocket 45and runs through recesses in the intermediate part 30 and in the topwall of the propeller casing 52. By means of splines the sprocket 45 isrelatively non-rotatably mounted on a shaft 56 which by means of tworoller bearings 57, 58 is rotatably mounted in the casing 52. Axialmovement of the sprocket 45 is prevented by a locking ring 49 which bymeans of screws, not shown, and via the inner race of the roller bearing57 and a spacing sleeve 50 clamps the sprocket 45 against a shoulder ofthe shaft 56.

The front end of the shaft 56 has a flange to which a propeller unit 60is secured by screws. The diameter of the shaft 56 is backwardlystepwise reduced, and the rear part of this shaft is of tubular shapeand has a central through hole 56a in which a tube 59 of considerablysmaller diameter than the diameter of the hole 560 is inserted between apipe plug 61 screwed into the rear end of the shaft 56 and a duct guide62 screwed into a widened hole in the front end of the shaft 56.

The tubular rear part of the shaft 56 extends through a chamber lVseparated in the casing 52. This chamber is defined by a sealing ring63, a spacer sleeve 64 and a hub 65. The chamber lV opens into a chamberIII in the hub 65v The spacer sleeve 64 and the hub 65 are axiallylocked by a nose 76 secured to the rear end of the casing 52. As willappear from the reference numerals of the respective separated chambersand from H0. H3 these chambers communicate through substantially radialducts in the members 64 and 65 and through inner internal ducts in thepropeller casing 52 and the intermediate part 30 with the previouslydescribed ducts or conduits ill and W for the supply of hydraulic fluidto the propeller assembly 24.

The chamber lV opens through radial holes in the tubular portion of theshaft 56 into the annular axial duct formed by the central hole 56a andthe tube 59 so that the ducts Ill and IV extend concentrically throughthe shaft 56 to the duct guide 62.

At the front end the part of the shaft 56 located outside the duct guide62 is in the form of a hydraulic cylinder 56b which has a fixed end wall66 through which a piston rod 67 displaceably mounted in the propellerunit 60 extends into the hyrdraulic cylinder 56b. The inside end of thepiston rod 67 is secured to a piston 68 in the hydraulic cylinder 56b. Atubular neck portion of the duct guide 62 is received in a dead end holein the piston rod 67.

Through internal holes 62a in the duct guide 62 the annular duct lVcommunicates internally with the tubular neck portion of the duct guide,and via radial holes in the piston rod 67 near the piston 66 and via theaxial dead end hole the final communication is established with onechamber of the hydraulic cylinder 56b. The duct ill in the tube 59communicates through internal holes 62b in the duct guide 62 directlywith the other chamber of the hydraulic cylinder 56b.

Upon increase of pressure in the chamber II] or IV of the hydrauliccylinder 56b the piston 68 and the piston rod 67 will be moved intoeither of two end positions in the hydraulic cylinder 56b and thepropeller unit 60.

The propeller unit comprises a rear bearing sleeve 69 and a frontbearing sleeve 70, which sleeves by means of flanges and screws, notshown, are secured to each other and together carry the other memberscomprised in the propeller unit 60. By means of screws extending throughthe front flange of the shaft 56 the propeller unit 60 is connected tothe rotary shaft 56 via the bearing sleeve 69.

At their common boundaries the bearing sleeves 69, 70 are in the form ofcollar-shaped bearing cups in which the propeller blades 51 arerotatably mounted and prevented from displacement by plates 51a securedto the inner bearing ends of the respective blades 51. Providedeccentrically on the underside of each plate 51a is an adjusting pin 51bby means of which the angular positions of the propeller blades 51 canbe adapted to the movement of the piston rod.

The piston rod 67 is displaceably mounted in the end walls of thebearing sleeves 69 and 70 and has secured to it a shifting member 72located between said end walls. The shifting member has three forklikegrooves on its irregular circumference which grooves receive theadjusting pins 51b. Upon displacement of the piston rod 67 and theshifting member 72 the adjusting pins 51b are acted upon and therebyturn the propeller blades 51 relative to the bearing sleeves 69, 70.

The shifting movement of the propeller blades 51 is limited by thecontact of the piston rod 67 with adjustable abutments in the respectiveend positions. The inner abutment or stop member is the duct guide 62,and the outer abutment or stop member is a stop screw 74 which isthreaded into the hublike outer portion 70a of the front bearing sleeveand is locked in adjusted stop position by a locking screw 75.

Secured to the end wall of the bearing sleeve 70 by means of screws, notshown, and mounted on the hub 70a is a nose 71. Through a steppedcentral hole in the nose a tubular sleeve 76 is threaded into the hub70a outside the screws 74, 75. Inserted into the tubular sleeve 76 is adetachable plug 77. In order to adjust the top position of the screw 74,the plug 77 is removed and different lock keyes are inserted into thetubular sleeve 76 for adjusting the respective screws 74 and 75 intodesired positions.

lclaim:

l. A drive unit for a vessel having a hull and a stern board comprisinga power plant mounted in said hull, a drive shaft extending rearwardlytherefrom, an outboard propelling assembly, said assembly including aforward section and an after section turnable in a horizontal planeabout a vertical axis and in a vertical plane about a transverse axisrelative to said forward section, a drive shaft extending forwardly fromsaid assembly, a universal joint disposed in said last-mentioned driveshaft to permit rotation of said after section, means for coupling saiddrive shafts eoaxially, a first sleeve fixed to said power plant andconcentrically mounted about said coupled drive shafts, said sleevepassing through an opening in the stern board so that substantially nothrust is imparted to said stern board, a second sleeve fixed to saidforward section of said propelling assembly and mounted inconcentrically nested relationship with said first sleeve. means forrotating said second sleeve relative to said first sleeve to rotate saidassembly about the axis of its drive shaft, a propeller unit fixed toand depending from the after section of said propelling assembly,propeller blades mounted in said propeller unit, a vertically disposedsteering post turnably connecting the forward section with the aftersection, beneath the universal joint, hydraulic means for rotating saidafter section about said vertical steering post to thereby rotate saidpropeller unit for steering the vessel, means for driving the propellerblades by the drive shaft of the propelling assembly and hydraulic meansvarying the pitch of said propeller blades from full forward thrust tofull rearward thrust, said hydraulic steering means and said hydraulicblade pitch varying means comprising annular grooves provided in one ofsaid sleeves to form. together with the other of said sleeves, a numberof annular hydraulic fluid distributing channels interconnected with thehydraulic steering means and said hydraulic blade pitch varying meansrespectively, whereby said steering means and said blade pitch varyingmeans may be operated independently of the angular position of the aftersection about the axis of the drive shaft in relation to the forwardsection.

